elfcore.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2
  3#include <linux/coredump.h>
  4#include <linux/elfcore.h>
  5#include <linux/kernel.h>
  6#include <linux/mm.h>
  7
  8#include <asm/cpufeature.h>
  9#include <asm/mte.h>
 10
 11#define for_each_mte_vma(cprm, i, m)					\
 12	if (system_supports_mte())					\
 13		for (i = 0, m = cprm->vma_meta;				\
 14		     i < cprm->vma_count;				\
 15		     i++, m = cprm->vma_meta + i)			\
 16			if (m->flags & VM_MTE)
 17
 18static unsigned long mte_vma_tag_dump_size(struct core_vma_metadata *m)
 19{
 20	return (m->dump_size >> PAGE_SHIFT) * MTE_PAGE_TAG_STORAGE;
 21}
 22
 23/* Derived from dump_user_range(); start/end must be page-aligned */
 24static int mte_dump_tag_range(struct coredump_params *cprm,
 25			      unsigned long start, unsigned long len)
 26{
 27	int ret = 1;
 28	unsigned long addr;
 29	void *tags = NULL;
 30	int locked = 0;
 31
 32	for (addr = start; addr < start + len; addr += PAGE_SIZE) {
 33		struct page *page = get_dump_page(addr, &locked);
 34
 35		/*
 36		 * get_dump_page() returns NULL when encountering an empty
 37		 * page table entry that would otherwise have been filled with
 38		 * the zero page. Skip the equivalent tag dump which would
 39		 * have been all zeros.
 40		 */
 41		if (!page) {
 42			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
 43			continue;
 44		}
 45
 46		/*
 47		 * Pages mapped in user space as !pte_access_permitted() (e.g.
 48		 * PROT_EXEC only) may not have the PG_mte_tagged flag set.
 49		 */
 50		if (!page_mte_tagged(page)) {
 51			put_page(page);
 52			dump_skip(cprm, MTE_PAGE_TAG_STORAGE);
 53			continue;
 54		}
 55
 56		if (!tags) {
 57			tags = mte_allocate_tag_storage();
 58			if (!tags) {
 59				put_page(page);
 60				ret = 0;
 61				break;
 62			}
 63		}
 64
 65		mte_save_page_tags(page_address(page), tags);
 66		put_page(page);
 67		if (!dump_emit(cprm, tags, MTE_PAGE_TAG_STORAGE)) {
 68			ret = 0;
 69			break;
 70		}
 71	}
 72
 73	if (tags)
 74		mte_free_tag_storage(tags);
 75
 76	return ret;
 77}
 78
 79Elf_Half elf_core_extra_phdrs(struct coredump_params *cprm)
 80{
 81	int i;
 82	struct core_vma_metadata *m;
 83	int vma_count = 0;
 84
 85	for_each_mte_vma(cprm, i, m)
 86		vma_count++;
 87
 88	return vma_count;
 89}
 90
 91int elf_core_write_extra_phdrs(struct coredump_params *cprm, loff_t offset)
 92{
 93	int i;
 94	struct core_vma_metadata *m;
 95
 96	for_each_mte_vma(cprm, i, m) {
 97		struct elf_phdr phdr;
 98
 99		phdr.p_type = PT_AARCH64_MEMTAG_MTE;
100		phdr.p_offset = offset;
101		phdr.p_vaddr = m->start;
102		phdr.p_paddr = 0;
103		phdr.p_filesz = mte_vma_tag_dump_size(m);
104		phdr.p_memsz = m->end - m->start;
105		offset += phdr.p_filesz;
106		phdr.p_flags = 0;
107		phdr.p_align = 0;
108
109		if (!dump_emit(cprm, &phdr, sizeof(phdr)))
110			return 0;
111	}
112
113	return 1;
114}
115
116size_t elf_core_extra_data_size(struct coredump_params *cprm)
117{
118	int i;
119	struct core_vma_metadata *m;
120	size_t data_size = 0;
121
122	for_each_mte_vma(cprm, i, m)
123		data_size += mte_vma_tag_dump_size(m);
124
125	return data_size;
126}
127
128int elf_core_write_extra_data(struct coredump_params *cprm)
129{
130	int i;
131	struct core_vma_metadata *m;
132
133	for_each_mte_vma(cprm, i, m) {
134		if (!mte_dump_tag_range(cprm, m->start, m->dump_size))
135			return 0;
136	}
137
138	return 1;
139}